Question

the number of molecules in 4.25g of NH3 is approximately

Answer 1

Molar mass of ammonia is 17g . So 17g ammonia contains 6.022×10^23number of ammonia molecules. So 4.25 g ammonia will contain (6.022×10^23×4.25)/17 = 1.5×10^23number of ammonia molecules. Each molecule contain 4 atoms (1 N atom and 3 H atoms).